Oracle subtring - substr function

The substr function extracts a substring from a string. Syntax:

substr( string, start position, length)

where the first position is 1 and the length of the substring is optional. Some examples

substr('substring', 2)     -- ubstring
substr('substring', 1, 3)  -- sub
substr('substring', -2, 2) -- ng

These examples have been tested on Oracle 8i, 9i, 10g, 11g, and it is highly likely that this syntax would not change in the future.